It is known to combine various woven, knit or nonwoven fabrics with plastic sheets or resin layers or to impregnate them with resins to form composite sheets intended for use in thermoforming and molding processes. For example, U.S. Pat. No. 5,075,142, to Zafiroglu and Japanese patent application publications 63-111050 and 63-162238 disclose such composite sheets. U.S. Pat. No. 4,298,643, to Miyagawa et al, discloses a particular fabric having an exposed pile layer, the back of the fabric being bonded or laminated to a thermoplastic sheet. Although moldable composites have been utilized widely in many applications, such composites are in need of improvement when intended for use in articles that are subject to severe abrasion, such as athletic shoe parts, luggage corners and surface layers, protective work clothes, heavy-duty sacks and the like.
Pile fabrics, such as velvets, velours, terry cloths, moquettes, tufted fabrics, and the like, each have a surface layer in which fibers are generally vertical to the surface of the fabric. Certain stitch-bonded fabrics, in which a fibrous layer is contracted and buckled by means of elastic threads attached to the fibrous layer to form a layer of pile-like groups of fibers, are disclosed by U.S. Pat. Nos. 4,773,238 and 4,876,128 to Zafiroglu. Generally, such pile or pile-like fabrics are not incorporated in composite sheets. Japanese laid-open patent applications 64-85614 and 64-85615 disclose a floor mat, which includes a tufted-monofilament pile, having an 8 mm height and a 0.08 g/cm3 pile fiber concentration, onto which a rubber resin is sprayed. The combination of the pile fiber and resin comprises 38% by weight of resin and has an average density of 0.13 g/cm3. Increases in the abrasion resistance of such floor mats could significantly improve their utility.
U.S. Pat. No. 6,063,473 entitled “Abrasion-Resistant Composite Sheet” to Zafiroglu discloses relatively thin pile or pile-like fabrics immobilized with resin to make abrasion-resistant composite sheet. The sheet comprises an upper outer surface, and a lower surface, a planar fibrous network located between and substantially parallel to the upper and lower surfaces. This composite sheet further comprises pile-like fibers that loop through the planar fibrous network and protrude generally perpendicularly from the planar fibrous network extending to the upper outer surface of the composite sheet, and a resin that immobilizes the pile-like fibers in a position generally vertical to the planar fibrous network. In accordance to the '473 patent, the stratum of pile-like fibers has a height in the range of 0.5 to 3.0 mm and a concentration of vertical pile-like fibers in the range of 0.05 to 0.5 g/cm3. The resin extends through the stratum of pile-like fibers from the upper outer surface to a depth of at least 0.5 mm, and more preferably throughout the composite. The resin-containing depth of the pile-like stratum has a density of at least 0.5 g/cm3. The composite sheet has a stretchability of no greater than 25%, a compressibility of no more than 25%, and a total unit weight in the range of 150 to 3,000 g/m2. Typically, the composite sheet comprises in the range of 30 to 90 percent resin, preferably at least 50% and most preferably at least 70%, based on the total weight of the composite. The composite sheet of the '473 patent has a concentration of the vertical pile-like fibers in the range of about 0.1 to 0.35 g/cm3. The density of the resin-containing depth of the pile-like stratum is in the range of about 0.7 to 1.0 g/cm3. The height of the stratum of pile-like fibers is in the range of 1 to 3 mm, and the resin preferably extends throughout the entire pile-like stratum. Typically, the composite sheet exhibits a 40-grit Wyzenbeek abrasion wear of no more than 50 microns per 1,000 cycles.
The '473 patent also discloses a process of making the composite sheet and a shaped article that has the abrasion-resistant composite sheet attached to at least a portion of the surface of the article. The composite made in accordance to the '473 patent can be expensive and can be stiff and inflexible due in part to the high amount of resin used to immobilize the pile or pile-like fabrics. Hence, there remains a need in the art for abrasion-resistant composite sheet that is more flexible, embossable and less expensive to make.